Rotary calciners (sometimes referred to as rotary kilns) are used for a variety of material processing applications. These high temperature machines process materials into a desired form by changing the state or composition of a material, or removing moisture. Unlike directly fired calciners, indirect rotary calciners are heated from the outside of an enclosed chamber. 

This gives them the ability to process materials that are fine or dusty, susceptible to contamination or combustion, sensitive to oxidation, or thermally sensitive. With this advantage, indirect rotary calciners have the ability to process a wide variety of materials.